This invention relates to an ink tank and a device for detecting ink remaining in the tank for an ink jet print head, and more particularly to an ink tank which is maintained at a pressure less than atmospheric and an ink jet print head including a device for detecting ink remaining in the ink tank.
Ink jet printers which print various characters patterns by discharging ink from a nozzle have recently become more popular. This recent popularity is due to the following advantages: noise is not produced as there is no impact on printing; printing may be on any type of print paper; printing contrast is high; energy required for printing is low; printing speed is high; a light weight and compact printer may be easily made; and so on. However, even though it is well known how to make a lightweight and compact jet printer, it has not been possible to apply this to a portable or pocket printing apparatus which may be freely carried about, since the printer ink escapes from the printer. It is also not possible for the conventional ink jet printer to print in all orientations of the printer. Additionally, the ink jet printer has a serious disadvantage due to the intrusion of bubbles into the ink tank. Accordingly, it would be desirable to provide an ink jet printer which may be freely carried about and can be printed in any print orientation. Additionally, it would be desirable to provide a means to prevent bubbles from intruding into the nozzle cavity and overcome the disadvantages of conventional ink jet printers.